Available prairie seed mixes may fall short for pollinators
[April 12, 2025]
As populations of bees and butterflies decline in the Midwest,
native prairie restoration becomes crucial. A new Prairie Research
Institute study found, however, that many commercial seed mixes used to
conserve and restore prairies may not have enough diversity or spring
flowering plants to fully support these pollinators.
“Imagine being an insect and waking up in the spring. You’re
metabolically stressed and you go to a habitat made just for you, but
there’s no food available for two months,” said Jack Zinnen, a PRI
wetland plant ecologist and lead author on the study. “That’s why a lack
of plant diversity is a big deal.”
The study compared 196 seed mixes designed for pollinators against 102
prairie remnants in eight states, finding that the seed mixes offered
less blooming richness and fewer early-blooming species.
“The irony is that you have these seed mixes that are explicitly for
pollinator conservation, but they will not be supporting pollinators
well for the first part of the growing season,” he said.
The paper, published in the journal Restoration Ecology, builds on
Zinnen’s previous research that included a survey of 557 plant vendors
selling native plants across the Midwest and investigated the contents
of commercial seed mixes. The new study compared the diversity of
wildflowers in pollinator-specific seed mixes to that of prairie
remnants, which are prairies that remain undisturbed by agriculture or
development.
Zinnen found that most mixes contained few, if any, plant species that
bloom before the second or third week of June. About 28% percent of
wildflower species in the remnants studied flower by the end of May,
compared with 0-13% in seed mixes.
Most mixes also contained fewer than 25 different plant species, at best
half the diversity of prairie remnants. Remnants contained 50 to 100
different wildflower species on average, with as many as 150 wildflower
species in some of the most diverse examples. Most of the seed mixes
were made up of a handful of grasses, with the majority of blooming
plants peaking in late July to early August.
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Pollinator restoration is becoming more popular, and the industry is
growing. Zinnen said encouraging the use of mixes with 40 to 50
different plant species, rather than just 25, would be ambitious but
would offer better support for pollinators and create a more
resilient habitat.
Another recommendation would be for mixes to include species that
become established easily, bloom in the spring, and tend to be
hardy. Some examples Zinnen suggested were wild strawberry, wild
garlic, golden alexander, spiderwort, and wild indigo.
The economics of species selection is also a consideration. Grasses
are less expensive than other types of plants and are used to fill
up the space in conservation areas. Some wildflowers are more
expensive than grasses but are popular because of their beauty. They
also contribute to a greater diversity.
In another recently published study, Zinnen and colleagues found
that some native plants — like orchids, pondweed, sedges, and ferns
— are harder to find for sale, meaning they’re underrepresented in
the commercial market. The native plants that are more widely
available tend to live longer, grow across larger areas, do well in
slightly disturbed habitats, and are often shrubs or trees. The
availability of plants and seed mixes from commercial vendors is
significant, the authors write, because it “can influence the
composition and outcomes of conservation, landscaping, and
restoration plantings.”
The greatest demand for seed mixes in the Midwest comes from private
landowners in the U.S. Department of Agriculture’s Conservation
Reserve Program and state agencies planting natural areas and
roadsides.
[Terri Casey
University of Illinois
County Extension Director]
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